Averaged Evoked Potentials to peroneal nerve stimulation are being recorded from surface electrodes placed over the human spine. The response progressively increases in latency rostrally and arises in the cauda equina and in spinal cord afferent pathways. The effect of maturation and spinal cord disorders on these potentials are being studied. Additionally these potentials are being studied in animals to provide information about their generator sources. Averaged evoked short latency potentials to median nerve stimulation which arise in peripheral nerve and central subcortical afferent pathways are being recorded from the human scalp. The effect of maturation and the effect of focal and diffuse neurologic disorders on these potentials is being investigated. Similar potentials recorded in cats are being studied to provide information about their generator sources. These studies should provide sufficient information which will determine whether these methods have clinical application in patients with neurological disease.